Dental impression-tray



L. V. ROBINSON.

DENTAL IMPRESSION TRAY.

APPLICATION FILED FEB. 17.1921.

Patented Apr. 26, 1921.

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Specification of Letters Eatent.

Patented Apr. 26, 1921.

Application filed February 17, 1921. Serial 110,445,714.

To all whom it may concern:

Be it known that I, LnsLIn V. ROBINSON, a citizen of the United States, residing at 2440 lVebb avenue, New York city, county of New York, State of New York, have invented certain new and useful Improvements in Dental Impression-Trays, fully described and represented in the following specification and theaccompanying drawings, forming a part of the same.

The present invention relates to a dental impression tray such as is employed by dentists for taking a plaster impression of the teeth in the mouth of a patient; and the object of the invention is two-fold: first, to furnish a tray which is readily manipulated in the mouth of the patient, andby the use of which the impression may be divided or split in two to facilitate its removal from the patients teeth; second, after the completed impression has been filled with plaster of Paris (thus forming a plaster cast or model of the patients teeth) to again split and instantly remove the impression from the hardened model.

This object is attained by the construction hereinafter shown and described in which the tray is made in two sections to fit re spectively the inner and outer sides of the gums, and joined by a connecting pivot, and the halves or sections provided with thumbpieces which operate when pressed, to turn the sections upon the pivot and at'the same time split the impression in two on the line of the teeth.

The wings of'the sections project at one side of the pivot and the thumb-pieces in the opposite direction, and when the thumb and finger are applied to the device at opposite sides of the pivot the sections may be either opened or closed by the movement of the fingers, thus enabling the operator to hold it closed while making an impression and press the sections apart when ready for removal from the teeth.

In certain cases a spring may be applied to the sections to hold them normally pressed together while taking the impression, and adapted to yield to pressure upon the thumb-pieces, to separate the halves of the tray.

The construction is of the simplest character, as it embraces only the two'sections provided with thumb-pieces and pivot-bearings, and in some cases the spring for holding the sections normally together.

The invention will be understood by reference to the annexed drawing, in which F gure 1 1s a'plan or top-view of the tray; Fig. 2 a bottom-view of the same; Fig. 3 a s1de-v1ew of the same; Fig. i a similar View with the nearer sections removed; Fig.

5 is a plan like Fig. l with the section.

pressed apart, and Fig. 6 is a cross-section on line w-x in Fig. 5, with the cast shown divlded in the sections.

The tray is inverted in making impressions of the lower teeth, but is shown in the opposite position in the drawing, and the parts are referred to in the positions as shown and described.

The tray as a whole consists of a base a, a, each sectlon of which has a side flange or w1ng 5, between which wings the plaster c is placed formaking an impression, as shown in Fig. 6.

The sections are curved longitudinally in the plane of the base, and the dividing line i (Z is correspondingly curved lengthwise of the base, and the adjacent edges of the sections are provided with flanges e, e, which normally lie in contact with one another when the tray is closed to make an impresslon. These flanges are complementally curved so as to close, upon a curved line lengthwise of the base, and thus operate when separated to split the impression into two curved parts.

Pivot-bearings g, g are attached to the bases of the sections and overlapped upon one another as shown in Fig. 2, to receive the pivot-pin h, which is inserted adjacent to the base of the sections.

A spring 2' is shown wrapped upon the pivot between the bearings, and its ends engaged respectively with the bearings of the two sections so as to press the sections normally toward one another.

At the opposite sides of the pivot, thumbpieces 76 are shown extended downward from the base past the pivot, so that when their free ends are pressed together by the finger and thumb of the operator, the sections are pressed apart.

At such times the flanges e, c are drawn apart leaving a space f between them as shown in Figs. 5 and 6.

When making the impression, these curved flanges c, c are embedded in the plaster of the impression, and when thus drawn apart they split the impression into two parts.

The lower ends of the thumb-pieces are.

curved outwardly so that the thumb and finger may grasp the tray firmly in all the operations incident to the use of such a tray.

with a transverse ridge, which forms an abutment or shoulder Z to resist any tendency of the thumb and forefinger to slip upwardly in manipulating the tray.

The thumb and finger press upon the thumb-pieces and wings simultaneously, above and below the level of the pivot, and are able to open or close the sections by pressing more strongly upon the part which will open or close the sections as desired. The device is therefore wholly operative without any spring to close the sections, and may be thus used if desired.

If used, the spring '5 is made of sulficient strength to hold the sections of the tray securely together in position for taking the impression, so that it may be handled when filling the tray with plaster, and in applying it to the gums, without the care required to hold it closed. Y

' It will be observed in Fig. 1 that the dividing line between the sections is curved in the plane of the base in correspondence with the natural curvature of the gums or teeth of which an impression is to be made.

The contiguous edges of the sections are therefore complementally curved, so as to open upon the curved line d lengthwise of the base of the tray.

It is immaterial whether the flanges e and 6 lie directly along the joint a of the base a, a, as they would perform the same function if they projected from the base adjacent to the j olnt.

In either case, the flanges e and e are complementally curved so as to split the-impression in line with the teeth.

It will be understood that the term thumb-piece includes any parts to which pressure can be applied for separating the sections, and that the shoulders on the outer lateral face of each member may be shaped and disposed in any suitable way to resist displacement of the thumb or finger.

Having thus set forth the nature of the invention what is claimed herein is:

1. A dental impression tray having two members joined by a connecting pivot, and

having, complementally curved adjacent edges provided with inwardly projecting flanges curved longitudinally upon the base of the tray.

2. A dental impression tray having two members joined by a connecting pivot, a spring applied to the pivot to press the members normally together, and thumbpieces upon the members for separating them when desired.

3. A dental impression tray having two members joinedby a connecting pivot, and provided with thumb-pieces upon the members projected below the pivot and operating to separate the members when desired.

4. A dental impression tray having two members joined by a connecting pivot, their basal portion provided with inwardly projecting flanges, and each of the members furnished with a projecting thumb-piece.

5. A dental impression tray having two members joined by a connecting pivot, their contiguous edges provided with inwardly projecting flanges and each of the members provided with a projecting thumb-piece,and a shoulder on the outer lateral face of each member to resist displacement of the thumb or finver. V

6. A dental impression tray having two members joined by pivot-bearings and a pivot-pin, their contiguous edges provided with inwardly projecting flanges curved lengthwise of the base, a spiral-spring wrapped about the pivot-pin and operating to press the members normally together, and thumb-pieces upon the members operating to separate the members when desired.

In testimony whereof I have hereunto set my hand.

' LESLIE V. ROBINSON. 

